The study assesses cognitive complaints in newly diagnosed patients with obstructive sleep apnea with no medical-comorbity affecting cognition. Cognitive complaints will be compared to healthy controls matched on age, sex and educational level. Factors related to cognitive complaints will also be assessed, including anxiety and depressive symptoms, complaints of fatigue and sleepiness, quality of life, psychological coping strategies and objective measures of cognition. Patients starting treatment for sleep apnea (continuous positive airway pressure or mandibular repositioning device) will be reassessed on all measures after 6 months of treatment to study the impact of treatment as usual on cognitive complaints and its related factors.